The research is directed to the identification and characterization of the enzymes which metabolize natural as well as foreign compounds in insects. All life stages of the house fly, M. domestica, the flesh fly, S. bullata, and the blow fly, P. regina are being studied. For the most part the enzymes are contained in the microsomal membranes or the supernatant fraction of insect homogenates. During the next grant period the work will be directed to the esterases which hydrolyze the natural JH and its synthetic analogs and to a further characterization of cytochrome P-450 in these species. Questions to be investigated include the specificity of the esterases, their tissue source, their multiple forms (isozymes), and species differences in activity. Research on cytochrome P-450 will include attempts to solubilize and resolve this enzyme into its multiple forms in the three species. Comparisons between susceptible and resistant insects will also be made.